Methanol → 6-Butyl-4-methoxycarbonyl-2-oxo-1,2-dihydropyridine
Reaction equation
S(Cl)(Cl)=O.[CH2:5]([C:9]1[NH:10][C:11](=[O:18])[CH:12]=[C:13]([CH:17]=1)[C:14]([OH:16])=[O:15])[CH2:6][CH2:7][CH3:8].[CH3:19]O>>[CH2:5]([C:9]1[NH:10][C:11](=[O:18])[CH:12]=[C:13]([C:14]([O:16][CH3:19])=[O:15])[CH:17]=1)[CH2:6][CH2:7][CH3:8]Participants
4
Procedure
12.5 ml (0.17 mol) of thionyl chloride are added dropwise with ice-cooling to a suspension of 29.25 g (0.15 mol) of 6-butyl-2-oxo-1,2-dihydro-isonicotinic acid in 200 ml of methanol and the mixture is stirred overnight at room temperature. It is concentrated to dryness and the residue is chromatographed on 450 g of silica gel (230-400 mesh) using dichloromethane dichloromethane/methanol 10:1. 29.6 g (94%) of colourless crystals of melting point 106° C. crystallised from dichloromethane, ether and petroleum ether.